Hubble's Sweeping View of the Coma Cluster of Galaxies

NASA's Hubble Space Telescope captures the magnificent
starry population of the Coma Cluster of Galaxies, one of
the densest known galaxy collections in the universe.

The Hubble's Advanced Camera for Surveys viewed a large
portion of the cluster, spanning several million
light-years across. The entire cluster contains thousands
of galaxies in a spherical shape more than 20 million
light-years in diameter.

Also known as Abell 1656, the Coma Cluster is over
300 million light-years away. The cluster, named after its
parent constellation Coma Berenices, is near the Milky
Way's north pole. This places the Coma Cluster in an area
unobscured by dust and gas from the plane of the Milky Way,
and easily visible by Earth viewers.

Most of the galaxies that inhabit the central portion of
the Coma Cluster are ellipticals. These featureless
"fuzz-balls" are pale goldish brown in color and contain
populations of old stars. Both dwarf, as well as giant
ellipticals, are found in abundance in the Coma Cluster.

Farther out from the center of the cluster are several
spiral galaxies. These galaxies have clouds of cold gas that
are giving birth to new stars. Spiral arms and dust lanes
"accessorize" these bright bluish-white galaxies that show a
distinctive disk structure.

In between the ellipticals and spirals is a morphological
class of objects known as S0 (S-zero) galaxies. They are made
up of older stars and show little evidence of recent star
formation, however, they do show some assemblage of structure
-- perhaps a bar or a ring, which may give rise to a more
disk-like feature.

This Hubble image consists of a section of the cluster
that is roughly one-third of the way out from the center of
the cluster. One bright spiral galaxy is visible in the upper
left of the image. It is distinctly brighter and bluer than
galaxies surrounding it. A series of dusty spiral arms
appears reddish brown against the whiter disk of the galaxy,
and gives rise to the idea that this galaxy has been
disturbed at some point in the past. The other galaxies in the
image are either elliptical, S0 galaxies, or background
galaxies far beyond the Coma Cluster sphere.

The data of the Coma Cluster were taken as part of a survey
of a nearby rich galaxy cluster. Collectively they will
provide a key database for studies of galaxy formation and
evolution. This survey will also help to compare galaxies in
different environments, both crowded and isolated, as well as
to compare relatively nearby galaxies to more distant ones
(at higher redshifts).

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Acknowledgment: D. Carter (Liverpool John Moores University)
and the Coma HST ACS Treasury Team